Because Im an engineer in a quality controlled field (Medicine), and my personal experience is that firms place too much faith in quality systems and not enough emphasis on quality employees.
I see lots of engineers and QA following a elaborate procedures with hundreds of checks, but not bothering to even read what they sign off on, so they can go golf all day.
People seem to think that you can engineer some process flow to prevent every error, but every process is garbage if the humans dont care or know what they are doing.
Every process is garbage is you dont hire workers with the right skills demanded by that process. In an effort to drive down costs, lots of companies try to make up for talent with process, with poor results, for both the companies and patients. you cant replace a brain surgeon with 2 plumbers and twice the instructions.